There are a variety of systems for monitoring and/or controlling any of a number of systems and/or processes, such as, for example, manufacturing processes, inventory systems, emergency control systems, personal security systems, residential systems, and electric utility meters to name a few. In many of these “automated monitoring systems,” a host computer in communication with a wide area network monitors and/or controls a plurality of remote devices arranged within a geographical region. The plurality of remote devices typically use remote sensors and controllers to monitor and respond to various system parameters to reach desired results. A number of automated monitoring systems use computers or dedicated microprocessors in association with appropriate software to process system inputs, model system responses, and control actuators to implement corrections within a system.
Various schemes have been proposed to facilitate communication between the host computer and the remote devices within the system, including RF transmission, light transmission (including infra-red), and control signal modulation over the local power distribution network. For example, U.S. Pat. No. 4,697,166 to Warnagiris et al. describes a power-line carrier backbone for inter-element communications. As recognized in U.S. Pat. No. 5,471,190 to Zimmerman, there is a growing interest in home automation systems and products that facilitate such systems. One system, critically described in the Zimmerman patent, is the X-10 system. Recognizing that consumers will soon demand interoperability between household systems, appliances, and computing devices, the Electronics Industry Association (EIA) has adopted an industry standard, known as the Consumer Electronics Bus (CEBus). The CEBus is designed to provide reliable communications between suitably configured residential devices through a multi-transmission media approach within a single residence.
One problem with expanding the use of control systems technology to distributed systems is the cost associated with developing the local sensor-actuator infrastructure necessary to interconnect the various devices. A typical approach to implementing control system technology is to install a local network of hard-wired sensors and actuators along with a local controller. Not only is there expense associated with developing and installing appropriate sensors and actuators, but the added expense of connecting functional sensors and actuators with the local controller is also problematic. Another prohibitive cost is the expense associated with the installation and operational expense associated with programming the local controller.
Accordingly, an alternative solution for implementing a distributed control system suitable for monitoring and controlling remote devices that overcomes the shortcomings of the prior art is desired.